The present invention relates to a scroll fluid machine such as a scroll vacuum pump or a scroll compressor.
A scroll fluid machine comprises a fixed scroll having a spiral fixed wrap; an orbiting scroll having an orbiting wrap engaging with the fixed wrap and being rotatably mounted around an eccentric axial portion of a driving shaft connected to a drive source and a cooling fan driven by the driving shaft to cool a plurality of cooling fins on the surface of the fixed scroll, a cooling path being formed axially in the driving shaft to allow a cooling gas to be introduced from one end and to be discharged from the other end thereby cooling heat generated under compression during transferring external air taken from the outer circumference to the center at a high-temperature central portion to allow bearings and sealing members in the vicinity of the center of the orbiting scroll to be cooled efficiently as disclosed in U.S. Pat. No. 6,109,897A.
However, in the scroll fluid machine, on the way of discharging a cooling-finished or warmed gas which cooled the cooling fins by rotation of the cooling fan to the outside, the cooling-finished gas flows into a gap between the cooling fan and a fan cover covering the cooling fan, so that the gas is likely to go into the cooling path from an opening provided at one end of the driving shaft. Thus, although non-used external air is introduced in the cooling path, the cooling path will not be cooled effectively.